The present invention relates generally to substrate processing and, more particularly, to control systems for semiconductor processing tools.
The fabrication of semiconductor devices, such as integrated circuits, flat panel displays, solar panels and other products often involves the formation of very thin layers and the patterning of such layers on a substrate, such as a silicon wafer or glass panel. Various techniques have been developed for semiconductor deposition and patterning processes that involve the use of sophisticated tools to carry out the necessary deposition, etching and other processing steps.
Manufacturers invest considerable sums of money in purchasing such tools. They also invest considerable sums of money in maintaining the tools and optimizing and qualifying the various the processing steps performed by each tool. Once a process performed by a particular tool has been optimized and qualified for a particular task (e.g., depositing a silicon oxide layer at a particular manufacturing step of an IC) any change to the process often requires that the changed process be requalified—an expensive and time consuming process. Thus, it may be desirable in some instances to have a particular tool perform the same function over the course of many years.
As a given tool gets older, however, some parts may be required to service the tool may no longer be available. For example, chemical vapor deposition (CVD) tool may include a computer control system that includes, among other components, a computer processor, RAM and hard disk memory storage and various I/O interfaces, such as a light pen display interface, that allow information to be exchanged between the tool and the control system and/or allow a user to input information to operate the tool. Certain semiconductor processes that run off the tool may be timed based on an algorithm that is dependent on the speed of processor or other variables that depend on the original components of the computer control system. As those original components are phased out of manufacture, replacing the components with new ones that perform the same or similar functions may have an undesirable impact on the timing or other variables of the process performed by the tool. This might require that the process be requalified, recalibrated, retested, etc., which can be very expensive and time consuming.